Tag Archives: Infection control

U.S. healthcare organizations increasingly face the most daunting medical challenge since the pre-antibiotic age. While pharmaceutical manufacturers hope for a new era of treatment that is still years from the market, the challenge—and preventative solution—is found in the built environment itself.

Healthcare’s perfect storm is not an industry secret. The Centers for Disease Control (CDC), the media, and industry experts often focus on the ever-increasing number of multi-drug resistant and environmentally adaptive pathogens. These microorganisms commonly overwhelm limited Environmental Service Department resources and navigate air-handling systems with ease, leaving healthcare providers to battle increasing numbers of infections with ineffective environmental tools. Some of these pathogens are so environmentally adaptive they may rebound to a majority percentage of their pre-disinfection levels within a few hours of surface disinfection.1

However, as Healthcare Infection Control Practices Advisory Committee (HICPAC) states, the problem is multi-faceted. The challenge is not solely an increase in more dangerous pathogens—advances in medicine and an aging population have provided an increasing amount of immune-compromised patients highly susceptible to infection, which may become an environment’s host population.

Providers work on patients, not buildings. Across the nation, Environmental Service Departments are losing staff, unable to keep up with surface transfer potentials throughout an active hospital. Architects and designers now have their most important role to date in providing successful patient care. They may design an environment that inadvertently accumulates, propagates, and circulates pathogens—or one which is the best ally in continually mitigating surface and airborne microbial health safety concerns.

If advances in medicine and microbial-adaptive abilities are the ‘anvil,’ then the lesser-discussed factors of finance, regulation, and litigation are the ‘hammer’ confronting healthcare clients. In 2009, Medicare and private insurance ceased payment for hospital-acquired infection (HAI) incident expenses, putting the brunt of this burden on individual facilities. Subsequently, federal International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD10) regulations continue to tighten the paperwork, documenting an increasing number of HAI incidents—meaning an ever increasing number of non-paying patients under federal reporting.

Public awareness has grown thanks to mandatory public reporting, millions of additional patients battling multi-drug resistant organisms (MDROs) joining the community, high-profile patients raising awareness, and CDC issuing press releases on the “superbug of superbugs.” This is now the age of HAI litigation, resulting in numerous eight-figure lawsuits.

How can architects and designers help?
Healthcare workers (HCWs), infection preventionists, and environmental service staff work harder than ever to achieve positive patient outcomes, but they have little control over the actual physical environment provided to them which supports their success. It is critical to address transmission and environmental pollution from C. Difficile spores, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE) microbes, Norovirus, and ribonucleic acid (RNA) influenza via unprotected vectors such as toilet aerosolization, surface transfer, humidity levels, and HVAC travel.

Healthcare-worker hand hygiene continues to be the best-known and recognized means of infection transmission. Numerous studies have been completed, documenting up to 40 percent of HCW hand contamination occurs from contact with the environment. Additionally, certain MDROs achieve 100 percent surface transfer success to multiple surfaces from origination, enabling exponential migration to what is quickly Sick Building Syndrome (SBS)—and once a facility is overwhelmed by microbial contamination, it can be hard to eradicate.

Patients may shed and exhale millions of pathogen particles daily, which may have weeks’ worth of environmental viability, putting a significant challenge on Environmental Services staff that may only have time to clean a surface once daily. Additionally, studies on microbial rebound have shown despite perfect cleaning and disinfection, surface porosity successfully harbors pathogen deposits such as MRSA and VRE that rebound up to 40 percent of their pre-cleaned level within a few hours, without recontamination.2

In most U.S. facilities, the existing minimum efficiency reporting value (MERV) filters do an excellent job of capturing 1-µm (0.04-mil) particles. Unfortunately, 0.3-µm (0.012-mil) particles—the same size HICPAC identifies as “potentially viable microorganisms, capable of indefinite suspension”—are often in the hundreds of thousands of particles per cubic foot. Particles are able to float from the lobby to the operating room, even picking up additional organic materials electrostatically from surfaces en route. Other environmental vectors—such as air dissemination to patient surfaces and the constant electrostatic particle interchange that occurs between surfaces and air—are well understood, but rarely addressed outside the highest level manufacturing facility clean rooms.

Specifying air-handling and surface products from a microbial perspective provides a direct and lasting impact on variables as diverse as:

Specifying for improved surface hygiene
Designers benefit from working with epidemiology, infection-prevention, and environmental hygiene client resources, along with expert consultant resources whenever available. The locations of highest touch deposits and most frequent interchanges—such as nurse stations or push plates—must be identified. Locations and equipment interacting with critical or multiple areas of a facility or its staff must also be noted, along with the potential traffic patterns of surface-borne microbes.

When selecting materials for high-contact surfaces, one must pay special attention to microscopic surface porosity and texture relative to cleanability, microbial rebound, pathogen reservoir development, and surface transfer potentials.

Self-disinfecting surfaces, or continually active antimicrobial materials and surface modifiers, should be specified to improve surface hygiene and cleanability. This also reduces the ‘anytime levels’ of colony-forming units (CFUs) of bacteria and resultant transmission potentials at high contact surfaces. Available materials include titanium dioxide (TiO2) and silicon (Si14) coatings, antimicrobial copper, and antimicrobial linen treatments.

Modifiers, such as Si14, virtually eliminate porosity, making surfaces inhospitable to deposits, and enabling them to be cleaned more efficiently. Being highly hydrophobic, this also prevents staining and improves the shine appearance of common materials. Active antimicrobials, such as TiO2, actually trap and destroy microbes and spores through a naturally occurring electrostatic property that incorporates continuous photo-catalytic oxidation. These coatings may be specified like any other coating, and then incorporated seamlessly by Environmental Services maintenance for periodic reapplication. The result is a space that cleans easier, has a lower microbial content, and diminishes health concerns rather than harboring and circulating them.

Engineered ultraviolet (UV) surface disinfection may be additionally employed at critical spaces, such as operating rooms, to guarantee surface sterility. Surface UV disinfection success is a function of output, distance, and exposure time, so these installations are typically best custom-designed for the specific space by a UV engineer.

Airborne prevention
In terms of preventing the spread of airborne infections, it becomes critical to work with mechanical engineers, infection prevention specialists, and epidemiologists to better understand the specific demands of a project. Employing independent IAQ resources adept in infection prevention can also assist in documenting bacterial loads and air dissemination potentials.

Similarly, the design professional should consider the electrostatic particulate dissemination and detachment continually occurring between air and surfaces—and how this relates to IAQ, surface hygiene, HCW hands, and transmission potentials.

Existing MERV filtration systems should be replaced with low-pressure-drop high-efficiency-particulate-air (HEPA) performance wherever possible, and not just in surgical areas. Ultraviolet germicidal irradiation (UVGI) systems should be specified at 800 to 25,000 microwatts per centimeter squared to dramatically improve IAQ—this also eliminates coil cleaning and the resultant respiratory irritant exposure to compromised patients of coil-cleaning chemicals. Even the best chemical coil cleaning does not completely remove biological material, and allows cleaning agents to travel downstream into occupied areas.

Critical or high-risk areas may greatly benefit from ‘first pass kill’ air disinfection specifications (up to 25,000 microwatts per cm2), which, per federal or military specifications will prevent the airborne transmission of any known microbe, and may affect majority reductions of C. Difficile spores. Bi-polar cold plasma systems are specified more commonly to address pollution challenges, such as helicopter or ambulance exhaust, but also provide a potent microbial reducing performance for occupied areas, after an air-handler.

Attention to detail can have substantial impact in infection prevention. The cardboard housing on common AHU pre-filters, for example, may sag in the presence of moisture as well as feed mold and microbes; similarly, a plastic laundry cart may travel from the soiled utility room to the ER to the neonatal intensive care unit (NICU) twice daily, contacting numerous surfaces and staff en route, while an elevator button may be touched by 600 people—including MRSA or VRE-positive patients—in one 24-hour period between cleanings.

The good news
Most of these specifications provide significant returns on investment (ROIs) completely unrelated to their environmental health safety benefits. Si14 surface treatment, for example, has a remarkable electrostatic repellency, which improves appearance, stain-resistance, and cleaning at critical surfaces. It also extends exterior window cleaning cycles by up to 75 percent.

UVGI systems may be used to reduce fresh air intake in administrative or other areas not subject to American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 170, Ventilation of Health Care Facilities, often resulting in up to 25 percent fresh air reduction and significant energy savings. Coil cleaning elimination alone can provide a quick return on investment and credits under the U.S. Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED) rating program. By recycling UV-sterilized cooling tower water, some facilities have saved tonnes in consumption annually.

Conclusion
Architects and designers now have many tools to create a safer environment, providing facilities ultimately with improved patient care and a much healthier bottom line. Surfaces and building equipment such as laundry carts and over-bed tables may be empowered to continually disinfect themselves. Further, air filtration can be improved to capture a larger number of microbial particles, and to sterilize the air at critical areas. Air movement and staff traffic may be anticipated to limit the potential of microbial migration from one patient to another.

Singular applications of these solutions have greatly lowered infection incidents. Many of these systems provide significant ROIs for owners, outside the targeted HAI reduction. Excellent resources exist from domestic manufacturers, as well from focused consultant and distribution organizations specializing in the wide range of healthcare environmental tools.

Notes1 For more information, see the article, “Intrinsic Bacterial Burden Associated with Intensive Care Unit Hospital Beds: Effects of Disinfection on Population Recovery and Mitigation of Potential Infection Risk,” by Attaway et al. It appeared in the December 2012 edition of American Journal of Infection Control. (back to top)2 See note 1. (back to top)

Scott Blevins is a managing partner at Portland, Maine-based I.C. Solutions. He has worked in healthcare construction management as a senior project manager and estimator since 2001, serving as a regular expert speaker to CSI, and engineering and environmental plant managers associations, on surface hygiene, antimicrobial systems, and air filtration. Blevins can be contacted via e-mail at sblevins@icscertified.com.

Designers and specifiers need to react quickly to increasing demands by healthcare executives, caregivers, and patients for better acoustic quality in their facilities.

High noise levels in hospitals have been shown to adversely affect patient and staff physiological conditions, including heart rate, blood pressure, respiration rate, skin conductance, and muscle tension.1 Noise decreases the duration and quality of the patient’s natural sleep cycles and inhibits recovery. Conversely, when the areas around patient rooms are quiet, occupants sleep better.

Restorative sleep decreases the need for pain medication, reduces patient fall rates, lowers average length of stays, and improves medical outcomes. In this new era of healthcare, acoustic performance is a top priority, not only in existing facilities, but also in every renovation, expansion, and replacement facility currently on the drawing board.

There are no other architectural surfaces more important and available to reduce noise and promote accurate speech communication in healthcare facilities than the ceilings. Considered to be no/low-contact ‘housekeeping surfaces’ by the Centers for Disease Control and Prevention (CDC), they do not significantly contribute to nosocomial infections rates. This allows a facility’s ceilings, in most areas, to be acoustically treated for either noise control or accurate speech communication.

In a 2007 Center for Health Design (CHD) whitepaper, “Sound Control for Improved Outcomes in Healthcare Settings,” the authors concluded installing high-performance acoustic ceiling panel systems is a key environmental strategy to reduce noise (and associated perceptions), as well as to have a positive impact on outcomes such as improved speech intelligibility and reduced perceived work pressure among staff.2

Changing demographics, changing healthcare designEarlier this year, a biannual benchmarking study conducted by the Beryl Institute showed more than 70 percent of healthcare professionals cited patient satisfaction as one of their top priorities during the next three years.3 Further, they said noise reduction was their top priority for improving patient satisfaction. To understand these findings, one must understand the series of events that has unfolded in the United States over the last eight years.

As baby boomers enter the phase of their lives where greater healthcare is likely to be required, and as obesity-related medical problems continue to increase, a deficit between Medicare revenues and spending was projected. In response, the 2005 Deficit Reduction Act authorized the Centers for Medicare and Medicaid Services (CMS) to implement its value-based purchasing (VBP) program. This program withholds one percent (incrementally increasing to two percent by 2017) of hospital financial reimbursements for care of Medicare patients. Those hospitals with higher quality and performance receive not only the one percent originally withheld, but also up to an additional one percent withheld from lower performing hospitals.

Currently, 30 percent of a hospital’s VBP score comes from the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey given to inpatients.4 This survey assesses their satisfaction with aspects of care such as doctor and nurse communication, pain management, and room cleanliness. At first, hospitals received full reimbursement for implementing the survey and reporting the results, regardless of the actual scores. But as of October 2012, actual reimbursements to hospitals are getting adjusted up or down, in part due to the facility’s acoustics.

In the HCAHPS survey, the question, “How often was the area around your room quiet at night: always, usually, sometimes, or never?” consistently scored the lowest. The current national top-box (i.e. “always”) score is only 60 percent compared to an average of 73 percent for all other metrics. Discharge Information has a top-box score of 84 percent. A high score on the quiet-at-night question is not easily achieved in existing hospitals.

A 2012 study conducted by Making Hospitals Quiet and the Beryl Institute showed only 12 percent of 241 hospitals trying to reduce noise in existing facilities judged their progress as “good” or “great.”5 A high score is not easy to achieve in new hospitals either. Twenty-five new (ground-up) hospitals built in the last six years have an average quiet-at-night score of 62 percent—only two percent better than the U.S. average.

The VBP program does not allow for even one low HCAHPS outlier. Many hospitals are seeing their reimbursement rates held down by their quiet-at-night score even though scores for the other metrics might be above achievement thresholds. There is also a strong indirect relationship between the quiet-at-night score and the scores of other questions. For example, when quiet-at-night scores increase, so do the scores for doctor communication, nurse communication, and even pain management.

Expanding Montana’s largest hospital, Benefis Healthcare Heart Institute, this Women’s and Children’s Patient Tower was designed by CTA Architects and L’Heureux Page Werner with elements taken from the natural environment, including real wood ceilings. The ceiling manufacturer worked closely with Sletten Construction and Just Rite Acoustics to bring this vision to life. Connecting the extensive campus, the serpentine concourse’s curved ceiling rely on snap-in panels that incorporate perforations and special backing materials, contributing to the quiet, soothing, healing atmosphere.

Entering evidence-based design
Evidence-based design (EBD) is the process of basing decisions about the built environment on credible research to achieve the best possible outcomes. A growing body of evidence attests to the fact the physical environment influences safety, patient stress, staff effectiveness, and quality of care provided in healthcare settings. At least three EBD studies have shown installing high-performance acoustic ceiling panel systems reduce noise propagation, creates the perception of a quieter environment, and improves speech intelligibility to enhance accuracy of staff communications.

In addition to the EBD studies involving high-performance acoustic ceiling panel systems, a 2008 whitepaper by the Center for Health Design and the Georgia Institute of Technology—“The Business Case for Building Better Hospitals through Evidence-based Design”—specified a list of eight “priority design recommendations” based on the strength of the evidence available and the impact on safety, quality, and cost. One of these priority design recommendations is to install high-performance acoustic ceiling panel systems to decrease patient and staff stress, reduce patient sleep deprivation, and increase patient satisfaction.

The whitepaper’s authors concluded:

Hospital leaders and boards face a new reality: They can no longer tolerate allowing preventable patient hospital-acquired conditions such as infections and falls, injuries to staff, unnecessary intra-hospital patient transfers that can increase errors, or have patients and families subjected to noisy, confusing environments that increase anxiety and stress. They must effectively deploy all reasonable quality-improvement techniques available.

To be optimally effective, techniques will almost always harness a bundle of tactics that, when implemented in an integrated way, will produce best results. Leaders must understand the clear connection between constructing well designed healing environments and improved healthcare safety and quality for patients, families, and staff, as well as the compelling business case for doing so. The physical environment in which people work and patients receive their care is one of the essential elements to address a number of preventable hospital-acquired conditions.

Roadmap to minimum acoustic requirements
The first step in understanding high-performance acoustic ceiling panel systems and how to specify them is to understand the standards and guidelines that establish minimally acceptable acoustic performance. From there, one can better understand best practices.

When trying to comply with the acoustic requirements in the different standards and guidelines for healthcare facilities, it helps to understand which document is the core source for acoustic performance criteria and design recommendations, and which other documents draw their content, in part or whole, from that core document.

Acoustics Research Council (ARC) represents several hundred members of the leading acoustical societies in the United States, including those from the Acoustical Society of America (ASA), the Institute of Noise Control Engineers (INCE-USA), and the National Council of Acoustical Consultants (NCAC). Since 2005, ARC has been responsible for developing the core document on acoustical performance criteria in healthcare facilities. The current version is the 2010 Sound & Vibration Design Guidelines for Health Care Facilities (v2.0), which is on a four-year revision cycle with the next version due out in early 2014.6 This core document is a minimum design requirement to ensure satisfactory acoustics and privacy in healthcare facilities of all types.

The main organization that references parts of this core acoustics document is the Facility Guidelines Institute (FGI). Founded in 1998 to provide continuity in the revision process of what were originally minimum construction standards from the Department of Health and Human Services (DHHS), FGI has produced the Guidelines for Design and Construction of Health Care Facilities—the 2010 edition is now used in some form by 42 states.7

The FGI Acoustics Working Group has become synonymous with ARC. Its efforts resulted in the 2010 version of FGI’s guidelines—the first edition in its 60-year history to contain comprehensive minimum criteria for acoustics in healthcare facilities. It recently revised the acoustics criteria in the 2010 version for the next issuing of FGI guidelines.

Revisions to FGI’s guidelines also occur on a four-year cycle. The 2010 version recently has been through a complete revision cycle, and the next version will be released early in 2014. In previous editions, only one guideline covered all types of healthcare facilities. In 2014, this will be split into two separate guidelines:

Guidelines for the Design and Construction of Hospitals and Outpatient Facilities, which will cover hospitals and outpatient facilities; and

Guidelines for Design and Construction of Residential, Health, Care, and Support Facilities, which will cover residential healthcare facilities such as assisted living, hospices, and nursing homes, along with related support facilities such as wellness centers, adult daycare facilities, and outpatient rehabilitation therapy facilities.

Some of the content in this new guideline existed in the previous versions, but it will be split off, expanded, and made to stand on its own in 2014.

Promoting health and wellness, About Family Fitness Center in Coral Springs, Florida, features a curving metal ceiling system installed by Acousti Engineering Company of Florida. Designed by Synalovski, Gutierrez & Romanik, the project’s aluminum ceiling system offers a modern aesthetic with the ability to control acoustics in noisy gymnasiums and exercise classrooms.

The FGI Acoustics Working Group cautions that the rapid pace of change in the U.S. healthcare industry (and in standards organizations) means each subsequent edition of the FGI’s guidelines likely will contain additions and revisions to the acoustical criteria to meet the healthcare industry’s growing need for guidance about sound, privacy, and noise.

In this table, with the exception of a few room types, the minimum required design room sound absorption coefficient is 0.15, which subjectively characterizes the room as ‘average.’ Although all room types are not listed in Table 1.2-1, there is still the overarching statement in section 1.2-6.1.3 that “all normally occupied spaces shall incorporate acoustic finishes.”

If one assumes the floor material is sound-reflective (e.g. terrazzo, vinyl composition tile [VCT], or laminate) and assumes the wall materials are also sound-reflective (e.g. painted gypsum board, glass, laminate, or finished wood), then meeting the required design room sound absorption coefficient of 0.15 falls mostly on the ceiling material.

The most popular acoustic ceiling panel systems are composed of mineral fibers, fiberglass, inorganic perlite blends, or perforated metal panels with an acoustical blanket. These panels are usually installed in a metal suspension grid to create the ceiling system. Meeting the 0.15 minimum requirement with these ceiling materials is not that difficult, many spaces can achieve this with minimum performing acoustic ceiling panel systems available from most ceiling manufacturers.

In general, specifying a ceiling panel with a noise reduction coefficient (NRC) of 0.50 will meet the 0.15 design room sound absorption coefficient in the FGI guidelines. A qualified acoustics consultant should calculate the actual design room sound absorption coefficients for the project to ensure requirements are being met.

At the 21st International Congress on Acoustics (ICA) in Montréal in June 2013, the Acoustics Working Group that edited the 2010 FGI guidelines into the 2014 version reported the minimum design room sound absorption coefficients may be increasing from 0.15 to 0.20, in FGI’s new Guidelines for Residential, Health, Care, and Support Facilities. At the time of the presentation, it was not clear whether the same change would be made in the Guidelines for Hospitals and Outpatient Facilities or if the value would remain at 0.15. This increase means that in most cases, minimal performing acoustic ceiling panels (i.e. NRC 0.50) will no longer meet the requirements in the FGI guidelines. Instead, as a general rule, moderate performing ceiling panels with an NRC of 0.70 will be required.

The Joint Commission (JC) is the not-for-profit organization that accredits and certifies more than 20,000 healthcare organizations and programs in the United States. The JC does not mandate use of FGI’s guidelines if another state or national standard is being applied to the project. For example, the Veterans Administration (VA) and Department of Defense (DOD) have developed their own guidelines. Beginning in January 2011, JC simply references the 2010 edition of FGI’s guidelines in its accreditation manuals.

CMS does not demand compliance with FGI’s guidelines either, but it does require compliance with an established standard and local building codes and requirements. Therefore, since many states call for compliance with the FGI guidelines, it makes them a back-door requirement for the JC and CMS in those jurisdictions.

The acoustic requirements in the 2010 version of FGI’s guidelines and its reference document, Sound and Vibration Design Guidelines for Health Care Facilities, are the basis for the acoustic requirements in the current version of the U.S. Green Building Council’s (USGBC’s) Leadership in Energy and Environmental Design (LEED) for Healthcare program (v.2009), as well as the upcoming edition (v4, currently in beta testing). Two LEED points are available for acoustic performance in Indoor Environmental Quality (EQ) Credit 2, Acoustic Environment.

Similarly, the acoustic requirements in the latest version of the Green Guide for Health Care GGHC (v2.2, 2007) are adopted from the 2006 version of the Sound & Vibration Design Guidelines for Health Care Facilities. It previously was titled the American Institute of Architects’ (AIA’s) and American Hospital Association’s (AHA’s) “Draft Interim Sound and Vibration Design Guidelines for Hospital and Healthcare Facilities.” GGHG, like LEED, has two points available for proper design of the acoustic environment (EQ 9.1 and EQ 9.2).

Under certain vibration conditions experienced in an earthquake, ceiling motion can increase and lead to near total failure of the acoustical ceiling. Mitigating these concerns, Marian Regional Medical Center features seismic perimeter clip products to meet the International Code Council (ICC) seismic performance requirements and provide a clean, sleek look.

Specifying high-performance acoustic ceiling systems
Early in the design process of every healthcare building, designers, specifiers, and healthcare executives must make an important decision: “Are we designing a minimally acceptable facility, or an optimal environment for generative recovery, healing, and health?” The answer to this question determines what type of ceiling will be specified and possibly need to be defended as the design, documentation, and construction take shape.

When specifying high-performance acoustic ceiling systems, there are three main acoustic metrics: the aforementioned NRC, along with articulation class (AC) and ceiling attenuation class (CAC). NRC and AC both indicate the ceiling’s ability to absorb sound inside a space and are fairly well correlated—generally, if NRC increases, so does AC. The main difference is the former is a better indicator of a ceiling’s (or other surface’s) ability to reduce general reverberation of noise as it reflects around inside spaces or down corridors throughout time. AC is a better indicator of how much a single reflection off the ceiling is attenuated.

If the general concern is overall noise and reverberation reduction, then the correct metric to specify is NRC. Values range from 0.0 (i.e. highly reflective) to more than 1.0 (i.e. very absorptive). NRC values of 0.60 or less are considered ‘low,’ from 0.65 to 0.85, ‘moderate,’ and above 0.90, ‘high.’ In rooms or areas such as inpatient corridors, centralized nurses’ stations, waiting areas, private patient rooms, and quiet rooms, reducing noise and reverberation are the primary concern. For these spaces, optimal performance equates to specification of very high NRC values in the range of 0.90 to over 1.0.

If the general concern is privacy and confidentiality between areas in close proximity that are not separated by enclosed isolating construction, then the correct metric to specify is AC. Values range from around 120 (i.e. high reflectivity, low confidentiality) to more than 230 (i.e. high attenuation, high confidentiality). AC values of 160 or less are considered ‘low,’ from 170 to 180, ‘moderate,’ and 190 and above, ‘high.’ In spaces where auditory privacy is a concern (e.g. semi-private patient rooms, pre- or post-operative communal areas, registration, financial services, and open consultation areas), optimal performance equates to very high AC values in the range of 190 to 230.

The next type of metric, CAC, is not a measure of noise absorption/attenuation, but instead a measure of the ceiling’s ability to block transmission of noise from the plenum above the ceiling down into the space below the ceiling. If there is no significant noise in the plenum above the ceiling, then CAC is not a metric of concern. However, when evaluating potential noise in the plenum, one must consider:

noise (or private conversations) that might flank over demising walls that do not extend all the way up to the underside of the slab above;

impact noise on the slab/roof above; and

noise that can break out of ductwork located close to the fans in the air-handling units (AHUs).

One of the biggest mistakes specifiers can make is to just select a moderate CAC value for the ceiling instead of taking the time to consider whether CAC is relevant. More often, CAC is not important. Since moderate to high CAC panels typically have significantly lower sound absorption qualities (i.e. NRC and AC), specifiers may be sacrificing acoustic comfort, privacy, confidentiality, and intelligibility for isolation from noise that does not exist in the plenum.

CAC values range from 0 (i.e. no ability to block transmission) to more than 40 (i.e. high ability to block transmission). CAC values of 25 or less are considered ‘low,’ from 25 to 35, ‘moderate,’ and above 35, ‘high.’ A good example of where CAC is important is an older medical office building where demising walls between treatment rooms stop just above the ceiling and the plenum above the ceiling provides a path by which private conversations easily pass between rooms. In cases such as this, CAC values for the ceiling should be 35 or higher.

It should be understood all these acoustic metrics—NRC, AC, and CAC—are single-number indicators, and are intended to represent the ceiling’s performance across a wide band of frequencies. However, the three metrics have been calculated from a more useful and telling data set indicating the ceiling’s actual performance at individual 1/3-octave bands (i.e. many narrower groups of frequencies). While it is acceptable to specify NRC, AC, and CAC, the specifications for high-performance acoustic ceilings should also include the minimum performance requirements at individual frequency groupings (i.e. 1/3 octave bands).

In rooms and waiting areas where reducing noise and reverberation are the primary concern, optimal performance equates to specification of high Noise Reduction Coefficient (NRC) values ranging from 0.90 to over 1.0.

Manufacturers must have these data in order to report NRC, AC, and CAC values. For example, in the medical office building where the demising walls stop at the ceiling and a common plenum provides a path for private conversations to be heard in adjacent rooms, the optimal ceiling specification would not be a single CAC value. Different ceilings with the same CAC value can perform significantly different in their ability to mute private conversations. Less critical is the CAC value. Most important is the 1/3-octave band transmission loss values in the 2- and 4-kHz octave bands. These are the most important frequencies for making speech intelligible. Therefore, to ensure private conversations remain private, one should specify the transmission loss (double pass per ASTM E1414, Standard Test Method for Airborne Sound Attenuation Between Rooms Sharing a Common Ceiling Plenum) not be less than 40 dB per 1/3-octave band in the 2- and 4-kHz octave bands.

Beyond absorbing noise for the sake of comfort, privacy, and confidentiality, another acoustic performance goal is accurate, intelligible, speech communication. In meeting or conference rooms, procedure rooms requiring team communication, worship centers, music therapy rooms, group education rooms, and geriatric care areas, the ceiling’s role is not one of absorption, but instead of passive reinforcement of the spoken word. Loud reflections off the ceiling help listeners hear and understand what is being said. It helps them feel closer to, and more intimate with, the people speaking. It helps them to concentrate and remember.

In these cases, ceilings should have low NRC and AC values (i.e. <0.30 and <140 respectively), and maximum, rather than minimum, levels should be specified. Optimally, one must ensure preservation of the most important speech frequencies by specifying absorption coefficients (alphas) shall not exceed 0.30 in any 1/3-octave band in the 2- or 4-kHz octave bands. However, as a precaution, it is important to ensure recommended reverberation times are not exceeded by sizing the room appropriately and, if needed, specifying absorptive materials on the floor and walls.

Acoustic materials and nosocomial infection rates
In early 2012, Chicago’s Rush University Medical Center opened its $654-million expansion, including a new emergency center, a neonatal ICU, and 304 acute patient rooms. During the design process, the nurse researchers were charged with determining whether there was any evidence demonstrating an increase in nosocomial infection rates due to the presence of acoustic materials. Finding none, and recognizing the noise control benefits, they recommended use of acoustic materials in the new hospital. The floors in the patient care areas are carpeted and the ceilings are high-performing acoustic ceiling panel systems.

Despite Rush University conclusions and a growing understanding about the safe and beneficial use of acoustics materials in healthcare facilities, there has been a lingering misconception that the use of acoustic materials in healthcare facilities, particularly hospitals, increases nosocomial infection rates. This misconception exists more so with healthcare providers than with designers of healthcare facilities.

In fact, the available information on the topic supports there is no relationship between the use of acoustic materials and hospital-acquired infection rates. Since 1970, CDC and AHA have advocated discontinuation of routine environmental culturing because rates of healthcare-associated infection have not been correlated with levels of general microbial contamination of environmental surfaces.

In 2003, CDC and the Healthcare Infection Control Practices Advisory Committee (HICPAC) published their Guidelines for Environmental Infection Control in Healthcare Facilities.8 These groups scoured the available evidence on the transmission paths for infection and developed guidelines for controlling the spread of infections in healthcare facilities.

Although microbiologically contaminated surfaces can serve as reservoirs of potential pathogens, these surfaces generally are not directly associated with transmission of infections to either staff or patients. The transferal of microorganisms from environmental surfaces to patients is largely via hand contact with the surface. Therefore, CDC’s guidelines discuss the impact of environmental surfaces on infection prevention in terms of the likelihood of hand contact.

Arkansas Children’s Hospital 23,969-m2 (258,000-sf) South Wing was designed by Cromwell Architects with the theme, “Healing is in our Nature.” The facility maintains a strong connection to the environment through both outside views and interior details. The ceiling systems were custom-shaped to resemble clouds and tree canopies.

CDC categorizes floors, walls, and ceilings as ‘housekeeping surfaces,’ further defining floors and ceilings as minimal hand-contact surfaces. The CDC guidelines include no recommendations against use of carpeting in healthcare facilities, but do suggest avoidance of carpet in areas around sinks such as in laboratories or janitor’s closets where they are likely to get repeatedly wet and in areas for immunosuppressed patients. However, carpeting offers limited noise control efficacy because it is a thin material and, as such, mostly absorbs only high-frequency noise effectively. The real opportunity for noise control and in some locations promotion of accurate speech communication remains to be the ceiling.

Discussion of ceilings in the CDC guidelines is limited. This is likely due to ceilings being no-contact surfaces (except during maintenance procedures). One could reasonably deduce that if there are no increased risks of nosocomial infections due to carpeting on floors then there would not be increased risks due to acoustical ceilings. The CDC’s guidelines encourage that ceilings (like all room surfaces) are well-sealed to help protect against undesired air infiltration, and that these surfaces do not collect an unusual amount of dust. There is no mention of cleaning ceilings beyond a general recommendation to keep all housekeeping surfaces visibly clean on a regular basis.

It should be noted all CDC recommendations on housekeeping surfaces are Category II, meaning “suggested for implementation,” as opposed to Category IA or IB, meaning “strongly recommended,” or Category IC, meaning “required by state or federal regulation.”

New criteria for acoustic success
In the past, the acoustic success of a hospital was largely judged by whether noise was present or not. Noise was bad and quiet was good. Still, silence is not the goal, as it makes high-acuity patients feel isolated. Nurse call rates increase. Further, a sonically sterile environment is a tremendous loss of opportunity. The new era of healthcare acoustics is not just about eliminating bad noises, but also about employing good sounds for their beneficial attributes.

Auditory landmarks are now used to aid wayfinding. The soft sounds of a baby cooing can lead expectant parents toward obstetrics. Positive auditory distractions, especially those that are interactive, can distract patients from their pain and loved ones from their stress. Nature sounds, whether real or recorded, are an important part reaping the benefits of having access to the natural world. Certain types of music can return worsened physiological conditions back to normalcy faster than manmade noise or silence. Acoustic experts currently are working on defining and developing guidelines for these more advanced aspects of enhanced sound quality in healthcare facilities.

In the future, the acoustic success of hospitals will be judged by how the total auditory experience contributes to recovery and satisfaction for patients, accuracy and stress relief in caregivers, and maximization of financial reimbursements.

Gary Madaras, PhD, Assoc. AIA, is a healthcare soundscaper and runs the Making Hospitals Quiet program for Chicago Metallic Corporation. He is member of the Acoustics Working Group revising the 2010 Facility Guidelines Institute’s FGI Guidelines, and chairs the subcommittee on healthcare acoustics for the Acoustical Society of America (ASA) Technical Committee on Architectural Acoustics. Madaras can be contacted via e-mail at madarasg@chicagometallic.com.